"It was certainly a humerus [upper part of a forelimb] but unlike any turtle known to the human race," Rich said.

He sent it off to two colleagues who specialized in primitive mammals. They had their own work to do, but eventually got around to the "humerus? turtle?" fossil.

The specialists determined that the fossil was in fact a mammal bone, from an early echidna, to be exact.

Echidnas are insect-eating burrow dwellers that, unlike other mammals, lay eggs. The two living species of echidnas, also known as spiny anteaters, occur only in Australia and New Guinea.

The mammal experts wrote up the scientific description for publication, and the newfound mammal was announced this week in the December issue of the Journal of Mammalian Evolution.

One Ton of Chocolate

Rich was thrilled that the dig had turned up an ancient mammal but somewhat dismayed at having to come up with a ton of chocolate, worth about U.S. $10,000.

Fortunately, Cindy Hann, a teacher and volunteer from the Dinosaur Cove dig, came to his rescue.

Hann had taught a boy whose father was the head of the Cadbury factory in Melbourne. He offered to make good on the chocolate bet.

"It turns out that it is technically impossible to make a cubic meter of chocolate, because the center would never solidify," Rich said. So the chocolate factory made a cubic meter of cocoa butter, the basis of all chocolate.

Because there was no way of knowing who had actually found the bone, Rich invited all of the volunteers who had participated in the Dinosaur Cove dig to the presentation of the prize at a local Cadbury chocolate factory.

After photos were taken of the giant slab of cocoa butter, the bone diggers were let loose in a room full of chocolate bars.

"It was a bit like Willy Wonka," Wilson said. "There were chocolate bars on the counters, the tables. We carried out boxes and boxes of chocolate."

Naming a newfound animal species is largely left up to the scientist who discovered the creature.

Kryoryctes means "cold digger" and reflects the fact that the animal was well adapted for digging and lived at polar latitudes. (A hundred million years ago, Dinosaur Cove, at the southern end of Australia, was well within the Antarctic Circle.)

As for the second part of the mammal's namecadburyiit's a safe bet you can figure it out for yourself.